Running boards are available on many automotive vehicles, such as pick-up trucks, and sport utility vehicles, to provide an easy ingress and egress to the vehicles. In some vehicles the running boards are fixed to the frame of the vehicle and are not intended to move in any direction. In other vehicles, the running board is movably mounted for selective positioning for the convenience of the user of the running board. For example a powered movement of the running boards is disclosed in U.S. Pat. No. 6,325,397, issued to David M. Pascoe, et al on Dec. 4, 2001. In this Pascoe patent, the running board is mounted on parallel linkages, which are coupled to an electric motor to effect a powered pivotal movement of the running board between a stored position and a deployed position. Other movable running boards are mechanically moved, such as is disclosed in U.S. Pat. No. 5,697,626, issued to Patrick K. McDonald, et al on Dec. 16, 1997, in which the running board is pivotally supported on the frame of the vehicle and vertically movable by a bell crank that pivotally moves the step portion of the running board. Such movable running boards are utilized solely for the purpose of providing convenient access between the ground and the passenger compartment of the vehicle.
The static stability factor (SSF) of a vehicle is a parameter used by the NHTSA to determine the rollover propensity of an automotive vehicle. A typical passenger car exhibits an SSF in the range of 1.3 to 1.5 while larger vehicles, such as the SUV's may have an SSF value in the range of 1.0 to 1.3, due primarily to the higher location of the center of gravity. The SSF factor is calculated as half the track width divided by the height to the center of gravity of the vehicle. The static stability factor also reflects the tilt table ratio and the centrifugal acceleration per gravity of the vehicle required to pass the point of unstable static equilibrium. Therefore, an increase in the SSF would indicate an increase in the roll angle at which the vehicle would become unstable and roll over to the side of the vehicle. If the effects of the suspension of the vehicle were ignored, passenger cars can be rolled statically to an angle of typically up to 52.4 to 56.3 degrees, or be subject to static lateral accelerations up to 1.3 to 1.5 times the force of gravity before experiencing a rollover event. Pick-up trucks and SUV's have a higher center of gravity resulting in a roll angle of typically about 45 to 52.4 degrees before experiencing a rollover event. When a vehicle is swerved onto gravel or earth during a potential rollover event, an increase in the resistance to the vehicle's speed, roll, yawing and sliding would shorten the time needed to bring the vehicle under control and stability.
In U.S. Pat. No. 1,231,531 granted on Jun. 26, 1917, to E. C. Shilling an automotive vehicle is equipped with a tilt prevention apparatus that is manually operated by pulling a lever to activate the device carried on the front and rear bumpers of the vehicle. The framework slides by gravity to the left or to the right of the vehicle to engage the ground in the event the vehicle goes into a ditch or the like. Similarly, U.S. Pat. No. 1,932,031, issued to S. Bellantese on Oct. 24, 1933, the vehicle carries a laterally shiftable apparatus that is mounted to the frame under the vehicle. The apparatus is activated directly by centrifugal force exerted while driving on a curve, which overcomes a set of springs retaining the apparatus in a central position.
In U.S. Pat. No. 5,931,499, granted on Aug. 3, 1999, to D. R. Sutherland, two pyrotechnically activated roll protection devices are disclosed. In one embodiment, laterally extending stabilizer beams are activated by a cylinder/piston with a pyrotechnic charge encased inside the wheel axle shafts. The second embodiment utilizes two pivoted beams attached to the vehicle body frame on each side to rotate about their vertical axes to attain laterally extending positions to prevent roll. Utilizing pyrotechnic charges is a costly design and packaging the cylinder/piston mechanism with squibs would be a significant challenge. Several embodiments of a rollover prevention device for trucks are disclosed in U.S. Pat. No. 6,588,799, granted to A. Sanchez on Jul. 8, 2003. In one embodiment, a laterally extendable arm slides by gravity until the ball on the end of the arm contacts the ground. In another embodiment, a vertically attached gear arm is pivoted at the top to a hollow arm. When the vehicle starts to roll, the hollow arm swings while engaging the gears and gets locked to prevent the vehicle from rolling. In still another embodiment, a sensor activates a vertically mounted piston mechanism that is fixed to the suspension system. The upper and lower pistons are driven by compressed air when roll is sensed to drive the lower piston to engage the ground and the upper piston to push the vehicle body back to a level position.
An inertia-based sensor is disclosed in U.S. Pat. No. 5,684,456, granted to Joachim Walter on Nov. 4, 1997, in which a cube-shaped weight is balanced by flexible arms and two extension measurement elements. The measuring element produces an electrical quantity such as a change in resistance or voltage. An electrical circuit would then be able to detect the roll and activate a remote device to prevent the roll. In U.S. Pat. No. 6,202,488, issued on Mar. 20, 2001, to S. M. Cash, an optical sensor based on inertia is disclosed. Such a sensor could be connected to an electronic control module to activate safety devices such as seatbelts, air bags in the event of a rollover, which is defined as being when the vehicle has rolled more than 75 degrees. Another inertia-based sensor is disclosed in U.S. Pat. No. 5,744,872, granted on Apr. 28, 1998, to Gasper Cairo in which a steel ball is mounted in a cup to generate an electrical signal in conjunction with an opaque projector associated with the movement of the ball.
Actuation of a deployable running board would require the sensing of a rollover event following by a rapid deployment of the running board at the lower side of the vehicle from a retracted position to an extended position so that the running board can engage the surface of the ground outboard of the adjacent vehicle tire to resist the continued rolling of the vehicle. Such a sensing and actuation device could be electronic in nature, and such sensing and actuation technology exists; however, a mechanical actuation mechanism would provide cost saving opportunities, as compared to the utilization of electronics, and provide a device that is not dependent on electrical energy being present at the time of the rollover event.
It would be desirable to provide an actuation mechanism that is operable to affect deployment of a laterally extendable running board on an automotive vehicle in response to the beginning of a rollover event for the vehicle.